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What is a Databse Query? 

A query is a question or a request for information expressed in a formal manner. In computer science, a query is essentially the same thing, the only difference is the answer or retrieved information comes from a database. A database query is either an action query or a select query. A select query is one that retrieves data from a database. An action query asks for additional operations on data, such as insertion, updating, deleting or other forms of data manipulation.

What is a query in SQL?

Query languages are used to make queries in a database, and Microsoft Structured Query Language (SQL) is the standard. Note: SQL and MySQL are not the same, as the latter is a software extension that uses SQL. Other language extensions of the language include Oracle SQL and NuoDB. Although Microsoft's SQL is the most popular language, there are many other types of databases and languages. These include NoSQL databases and graph databases, Cassandra Query Language (CQL), Data Mining Extensions (DMX), Neo4j Cypher and XQuery.

How to run a SQL query against a database

If you’re unfamiliar with database queries, running a SQL query on your database may seem daunting. However, it isn’t as complicated as you might think. 

To run a SQL query on your database, you’ll need:

1. A database engine: Database engines serve as data repositories. There are countless database engines available, including Oracle, MySQL, SQL Server, Db2, and PostgreSQL. Smaller organizations often opt for MySQL, PostgreSQL, or other free database engines, while larger companies generally use larger, robust ones. Once you choose your database engine, installation is relatively straightforward.
2. A SQL client: You’ll also need a SQL client to communicate with your chosen database engine. Some database engines will automatically install SQL clients, but others may require you to download, install, and configure a SQL client after installing the database engine.
3. A SQL query: Finally, you’ll need to craft and run a SQL query. SQL queries vary in complexity, allowing you to do everything from retrieving all results within a specific table to filtering for particular results and adding new data.